Object 187, it was another project of Soviet MBT which was in development in 1986-1988. Object 187 was under development in parallel with Object 188 (which we will know as T-90). Main goal for this program was to increase protection of T-72 to T-80U level. But UVZ team viewed Object 187 as future Soviet/Russian MBT, so they went beyond simple increase of armor.
Engineers changed shape of the frontal part of T-72 hull, which now did not had a famous weakspot, that was jokingly called "cleavage" (weakspot in upper frontal plate becuase of the driver optics, all T-64s, T-72s and T-80s have them).
Object 187 also had new welded turret, which was implemented later in ~2004-2005 in T-90A and new gun mantlet.
Main gun was D-91T (2A66) from Factory N9 in Sverdlovsk, which is believed to be more powerfull gun than 2A46. It was equipped with muzzle brake to decrease recoil.
Object 187 was planed to be equipped with new ERA, known as "Malakhit", which later will become Relikt ERA (ERA with 2 opposite moving plates instead of 1 in Kontakt-5).
6 Objects 187 were build for testing, with prototype number 5 and 6 being most advanced. N1 had 840HP V-84MS engine, N2 was tested ith KD-34 1000 HP V-shaped diesel engine, N3 received engine compartment from T-80U with GTD-1250 gas turbine, developing 1250 HP. N4 got fancy X-shaped 1200HP A-85-2 diesel from Chelyabinsk. Weight of new tank reached 55 tons. Overall, internal layout of the vehicle was made less cramped, which would allow to increase modernisation potential for a tank in the future.
Object 187 was never adopted to service because new Russian Federation state went with cheaper Object 188. Several prototypes survived in Kubinka museum "sump", in bad conditions.